This protection contains a "fat" track on tracks 35 and 36, meaning it is one track that is twice as wide, or to explain another way-- the exact same data on two tracks lined up perfectly.

This protection will work in VICE since it aligns all tracks, but on a real 1541 it is difficult to remaster due to the lack of hardware assistance in laying down tracks exactly aligned. It can be done with the proper drive speed and timings.